Supercedure cells?

I have 10 hives. 7 are brand new nucs. Two of the newly hived nucs have supercedure cells (small queen cell on frame side)
They have plenty of space still, but I put a second box on anyway- for air/space.
One of my second year hives just swarmed. As I was collecting the swarm I grabbed a frame of brood from a 2nd year hive to coax them- first frame had a supercedure cell! They also have lots of space! By lots I mean 3-4 empty frames per box.
When you come across a queen cell like this- what should you do?

Have you seen your queen?
Something like this you need to keep an eye on, sometimes they will build them. It's being there is not a great concern, but if they put something in there then it's a different matter entirely.

Yes- I was concerned so I actually squished it. Probably not the best move- if they are going to leave and I miss them- I'm queenless. Been there done that already! Just felt like I needed to slow them down. In my opinion they have no reason to swarm. Will be through them thoroughly this weekend!